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Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 65,200	$ 58,000
Contribution to pension plan in excess of minimum required contribution	$ 0	0	$ 0
Number of consecutive years used for compensation calculation	5 years
Investment strategy, percentage in long-term growth	97.00%
Investment strategy, percentage in near-term benefit payments	3.00%
Maximum percentage of securities purchasing allowed of the portfolio at any time	5.00%
Maximum market value purchase percentage allowed of any one issuer	8.00%
Expense included in salaries and employee benefits			1,300
Postretirement Benefit Plan, Accrued liabilities	$ 151	$ 149
Estimated future net loss for the plan that will be amortized from accumulated other comprehensive income	750
Estimated future prior service credit for the plan that will be amortized from accumulated other comprehensive income	$ 72
Maximum percent of participant's contribution match	4.50%
Securities Less Than Aquality [Member]
Defined Benefit Plan Disclosure [Line Items]
Maximum percentage of securities purchasing allowed of the portfolio at any time	13.00%
Commercial Mortgage Back Securities And Assets Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Maximum percentage of securities purchasing allowed of the portfolio at any time	10.00%
Portfolio Concentration Commingled Trust Fund1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets	15.00%	14.00%
Portfolio Concentration Commingled Trust Fund2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets	6.00%	6.00%
Portfolio Concentration Short Term Investment Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets	6.00%	6.00%
Investment Firm One [Member]
Defined Benefit Plan Disclosure [Line Items]
Portfolio management, controlled percentage	59.00%	58.00%
Investment Firm Two [Member]
Defined Benefit Plan Disclosure [Line Items]
Portfolio management, controlled percentage	37.00%	38.00%
Defined Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Portfolio management, controlled percentage	4.00%	4.00%
First 3% Of Participant's Contribution [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage employer matches of the employee's percentage contribution matched	100.00%
Percentage for which the employer contributes a matching contribution	3.00%
Next 3% Of Participant's Contribution [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage employer matches of the employee's percentage contribution matched	50.00%
Percentage for which the employer contributes a matching contribution	3.00%
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Unfunded pension liability	$ 1,900	$ 2,100
Pension expense	$ 194	$ 88	$ 408

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Amount of liability, recognized in statement of financial position, for defined benefit pension plan. Excludes other postretirement benefit plan.

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Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

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